Joyce has labelled the PM's comments "inept" as the working relationship hits a snag.

Opposition Leader Bill Shorten said yesterday “the time is well past the hour” for Prime Minister Malcolm Turnbull to sack his Deputy Prime Minister.

So why can’t Turnbull give Barnaby Joyce the old heave-ho?

Turnbull is hamstrung by the political marriage that is the coalition. Under the so-called coalition agreement, that is never made public, the Nationals support the Liberals to form government based on a number of conditions.

Convention dictates that the leader of the Liberals is the prime minister, while the leader of the junior coalition party becomes deputy prime minister.

The deputy is automatically elevated to Cabinet, along with the party’s deputy leader and leader in the Senate.

This was why there was so much jostling over who won the deputy’s spot after Fiona Nash was booted from Parliament last year.

Barnaby Joyce addresses the media following a week of scandal.

The West Australian

Barnaby Joyce addresses the media following a week of scandal.

The Nationals’ total ministerial representation is a quota calculated according to how many Lower House seats the party wins. But who fills all of these ministerial positions, including party leader, is a matter for the Nationals party room.

Just as the Nats don’t get to pick who is Liberal leader and prime minister, the Libs have no say in who leads the Nationals.

Constitutionally, Turnbull could strip the ministerial position from Joyce, but doing so would effectively blow up the coalition agreement and end the convention that has been a mainstay of Australian politics since 1923. Australia has had 117 years of Federal government, with 57 of those governed by a conservative coalition, with Labor the common enemy.

Turnbull chose to put public pressure on Joyce this week, making it clear he did not think he was fit to lead the Government in his absence and should reconsider his position.

But for Joyce to go, it will take the 20 other MPs in the Nationals party room to come to the same conclusion.